A new wearable device developed by researchers at Northwestern University could offer a significant shift in how breast milk intake is monitored during breastfeeding.
The soft, wireless sensor wraps gently around the breast and transmits real-time data to a smartphone or tablet, allowing parents and clinicians to see exactly how much milk is being transferred during a nursing session.
This development addresses a long-standing challenge in infant feeding: the difficulty of knowing how much milk a baby consumes at the breast. Until now, measurement methods have relied on pre- and post-feed weigh-ins or switching to bottle feeding — both of which can disrupt breastfeeding routines and increase anxiety for parents.
According to Professor John A. Rogers, one of the lead developers, the device uses a technique called bioimpedance — a small electrical signal that changes as the volume of milk in the breast changes — to track milk intake during feeds. The results are displayed live on a mobile app.
Supporting Parents and NICU Babies Alike
While the device could offer peace of mind to any breastfeeding family, its potential impact in neonatal care is particularly noteworthy. In the NICU, where feeding volumes often need to be tightly controlled, this sensor could support direct breastfeeding where bottle feeding has typically been required for measurement purposes.
“Knowing exactly how much milk an infant is receiving during breastfeeding has long been a challenge for both parents and healthcare providers,” said Professor John A. Rogers, lead developer of the device. “This technology eliminates that uncertainty.”
Knowing exactly how much milk an infant is receiving during breastfeeding has long been a challenge for both parents and healthcare providers
Professor John A. Rogers
Dr. Jennifer Wicks, a pediatrician and mother of three involved in the study, added, “There are several advantages to breastfeeding at the breast compared to feeding breast milk with a bottle. First and foremost, that skin-to-skin bond is beneficial for both babies and moms. Additionally, milk production is oftentimes stimulated better by actual breastfeeding.”
How It Works
The device uses safe, low-level electrical signals to detect changes in the electrical properties of the breast as milk is removed. These subtle changes are captured and converted into accurate milk volume readings. After a one-time calibration session using a breast pump, the device can be used during regular breastfeeding.
Testing so far has shown the device’s readings closely match both bottle-feeding measurements and the traditional “weigh-feed-weigh” method. It has been trialled on new mothers both at home and in NICU settings over several weeks.
What’s Next?
The team hopes to make the technology even more accessible by integrating it into breastfeeding bras, improving usability across skin tones, and eventually adding features like milk production tracking and fat content analysis.
This innovation has the potential to ease a major pain point in breastfeeding – the uncertainty. As Dr. Wicks explained: “Breastfeeding can be extremely emotional for mothers, in part due to the uncertainty surrounding how much milk their babies are getting. It can come with a lot of sadness because mothers feel anxious and like they aren’t doing a good job. Oftentimes, mothers experience anxiety, frustration or symptoms of depression and give up on breastfeeding altogether.
Breastfeeding can be extremely emotional for mothers, in part due to the uncertainty surrounding how much milk their babies are getting.
Dr. Jennifer Wicks
“There are many factors that make breastfeeding difficult. Being able to remove one piece of uncertainty and being able to help reassure them that they are producing enough milk will really help decrease some of that stress and anxiety. “
The study, “A compact, wireless system for continuous monitoring of breast milk expressed during breastfeeding,” was supported by the Querrey Simpson Institute for Bioelectronics, the Defense Health Agency, the National Research Foundation of Korea and the Haythornthwaite Foundation.
Source:
Journal reference:
Kim, J., et al. (2025) A compact, wireless system for continuous monitoring of breast milk expressed during breastfeeding. Nature Biomedical Engineering. doi.org/10.1038/s41551-025-01393-w.
